Medical evidence indicates that the mental and/or physical health of people may be affected by exposure to light. In particular, a condition know as seasonal affective disorder (SAD) has been recognized wherein certain individual depressive patients exhibit a periodic, yearly recurrence of their affective illness. These recurrences tend to occur during seasonal periods of low level and/or short duration light such as in late fall and winter. It has been discovered that the mental outlook of people exhibiting SAD symptoms, as well as non-seasonally depressed people, may be significantly improved by light therapy.
Light therapy involves exposure to light of predetermined intensities for predetermined periods of time. Exposure of the retinas to bright light stimulates the pineal body within the brain to regulate the production of melatonin, a mood-altering hormone. Preliminary clinical studies indicate that bright light of 2500 lux is effective in producing a marked remission rate in depressed persons. Bright light as low as 500-1000 lux and as high as 10,000 lux has also been shown to affect melatonin production. Differences in individual sensitivity affect the response to bright light. The duration of exposure is also a factor.
Generally, persons undergoing a regimen of light therapy have shown improvement within 2-4 days after commencement of therapy. While clinical studies have not established an optimal period of treatment, treatment periods of one to several weeks, with daily exposure periods that may extend over several hours, have generally been found to provide a significant remission rate. Treatment periods of such duration, however, when conducted in a clinical environment, are extremely inconvenient for the vast majority of the population. A need exists, therefore, for an apparatus that will allow people to undergo light therapy within their living environment, at their convenience.
In addition, most people experience affective stress levels in the conduct of their daily affairs. A need exists to provide conditions under which people can reduce the stress levels that may accumulate during the day. It has been recognized, however, that the human visual system automatically and continuously searches for patterns and dark-light boundaries within the visual field. Upon finding such patterns and/or dark-light boundaries, the brain works on a subconscious level to abstract meaning from such patterns and/or dark-light boundaries. This work occupies the brain to a great extent during waking hours.
This abstractive process may interfere with the reduction of stress levels. Therefore, a need also exists for a means for temporarily reducing or eliminating the abstractive process engendered by the human visual system. Meditation, which provides beneficial psychological and physical effects, may be one means of reducing the effects of the abstractive process. Light therapy under controlled conditions is another means of reducing the effects of the abstractive process.
It is also know that people's biological clocks may be disrupted due to the demands of their daily affairs. Disturbances in biological rhythms due to such conditions as jet lag, long working days, irregular work shifts or even such a mundane thing as sleeping late can have a detrimental effect on a person's efficiency and judgment. Recent experiments have shown that a regimen of light therapy, under controlled conditions, may be utilized to shift the sleep-wake cycle to alleviate disturbances in biological rhythms. A controlled light therapy regimen has also been shown to be useful in the treatment of sleep disorders.